Get a username
The first thing that you need is a project.im username and password. This can be set up here.
Use the web chat
If you want to start to chat straight away, you can log in to the project.im web chat here. it is a full-featured web chat interface with many features and runs in your web browser.
Connect your own application
As project.im is a standards-based service, you can choose any XMPP or Jabber client application to connect. You can find more information within the frequently asked questions page.